Pneumatic hammer



Aug. 1 4, 1-923. 3,4643% E. CU-RTI PNEUMATIC HAMMER Filed July 50. 1920 Patented Aug, l i, i923, r

ERNESTO CURTI, Q1 .JIILAN, ITALY.

PNEUMATIC HAMMER.

Application filed July 30, 1920. Serial No 400,225.

To all whom it may concern, A stem 8 extends therefrom and projects Be it known that I, ERNESTO Court, a into a cylindrical guide sleeve The stem subject of the King of Italy, residing at 8 has helical grooves 10 on its surface, which Milan, in the liingdom of Italy, have inengage similar teeth on thehub of apinion 5'ventedcertain new and useful Improve- 11. A plate 12 secures the pinion ll in ments in Pneumatic Hammers, of which the place and said pinion is capable of rotating, following is a specification I but is prevented from any axial displace- This invention relates toipneumatic hamment by said plate. Pinion 11 meshes by mers'ot' the type actuated by a single piston means of "an intermediate idle pinion 13,

10 compressor, and in'which a single pipe conwith gear 14, whereby the rotary motion nects the compressor to the hammer. of pinion 11 is transmitted to gear 14, In the annexed drawing two alternative which 13 incapable of a displacement along embodiments of a sinele piston compressor the axis of cylinder 1, but can freely rotate actuatedhammer are shown. about this axis. By means of a key or the 5 Referring to the drawing, like, the stem of the tool 5 is fixed to rotate Figure 1 is a sectlonal elevation of one with the gear 14 and is capable of axial form'of hammer, movement relatively to said gear. Fig.1 2 1s a cross section of the guiding ()ne of the toothed wheels is associated stem for the auxlhary piston of the hamwith a device wlnch permits of the rotation ZO mer. taking place in only one direction. This F ig. 8 is a yertical sectional View of a device consists of a toothed disk fixed to the modificationi: gear lland cooperating with a pawl dia- The single piston compressor used'in congrammatically shown at 11. Between the nection with the inyent-ion is not illustrated outer face of the auxiliary piston 7 and the 25 intlie dra-win'g but is of the common conhead of the cylinder Gaspring 15 is fitted for structiofi. such asfis disclosed by my preaiding in moving; the piston in one direcvious Italian Patent No; 172,720, and is protion. The cylinder 6 has, near its head, a vided witha single piston traveling to and hole 17 to the atmosphere, and a port 16 fro within a single cylinder ()nly one valve places the lower portions of cylinders 1 and is .used and a single air pipe only extends 6 in communication. The t-ool5 and its stem from the compressor to the hammer. In are bored axially, and the extension 8 and case two ormore compressors are grouped 'the piston 7 are also provided with an axial 9 for the sake of compactness of the working bore. 7 V 1 systemof tools, or for thesake of an easier Thehai'nmer operates as follows: control from a single motor, each compressor Assun'iine the hammer 2 to be at the upper controls a hammen the hammers being as end of its stroke, air pressure from pipe 4 many as the grouped compressors. j is injected into the cylinder 1 and this forces The hammer according to the embodithe hammer 2 downwardly against the tool ment shown in Fig. 1 comprises a cylinder 1 stem. While lowering, the hammer com- 40 h ing} bore in which the hammer piston presses theair within the lowerspace of cyl- 2 reciprocates. A hollow trunk-shaped inder Liand. owing to the port 16, this air stop 3 serves to limit the stroke of the recippasses into the lower space of the cylinder rocating hammer piston at the outer end of 6, and the auxiliary piston 7. As the pisits stroke. 1 is the air. pipe from the comton 7 rises it compresses the spring 15. As 45 pressor which opens into the bore of the soon as the supply of pressure airlirom 4 cylinder 1 atitheupperend thereof, and adceases, and the suction exerted from the cyljacent to the cone-shaped stop 3. The stem inder of the compressor commences, a de- 0 of the tool 5 pr0'jects into the bore of the pression takes place above thehammer 2 and cylinder 1' to receive the blows struck by the latter quickly makes its upward stroke, 50 thehainmer piston 2. not only because of this depression, but due At one side of thecylinderl, and integral to the stored air pressure within cylinder 6, V therewith, another. cylinder 6 istprovided, assisted also by the spring lowhich is ex- "wherein an auxiliarypiston 7 reciprocates. paneling during the upward stroke of the For hammer 2. The momentum of piston 7 at the end of its downward stroke maintains within the lower space of cylinder 6 the air pressure which assists the hammer while rising. For the purpose of maintaining within the lower spaces of cylinders 1 and 6, the required quantity of air, the hammer 2 uncovers before reaching its upper position, a port 18 which through the bore of cylinder 6 and port 17 establishes a communication between the atmosphere and the inner lower spaces of cylinders 1 and 6.

Piston 7 reciprocates within the cylinder (5 in synchronism with the hammer 2. Owing to the helical grooves of the extension 8 and to the dog 11 mentioned above, as the piston 7 moves in one direction the toothed wheels 11 and 14: will be rotated thereby,

whilst as. the piston 17 moves in the oppo site direction, the toothed wheels will not rotate, and to the piston 7 a rotary motion Wlll be imparted. Owing to the momentum V of the piston 7, the resistance offered by the toothed wheels, will be overcome so that a rotary motion of the piston, when. the toothed wheels are rotated, will not take place. The axial bore of the stem 8 is provided to permit air .to enter and be'discharged from the chamber 9.

The axial bore of the tool 5 and its stem permits a jet of air from cylinder 1 to be projected from the outer end of the tool, to clean the surface operated upon by the latter, and to prevent dust "from entering the inner chambers of the machine.

By the improved construction the tool is pushed against the surface to be worked and at the same time is rotated about its axis. i

If it is desired to utilize the compression trom the compressor for raismg the hammer piston, thesuction from the compressor may be used to. lower the hammer, and thehammer can be constructed as shown in Fig. 3. In this modification 19 is the cylinder,20 the hammer proper, 23 the tool, 21 (at the lower end oi the cylinder) the pipe from the com prcssor, 22 (at the upper end of the cylinder) the pipe to the auxiliary cylinder 6 as in Fig. 1. .In' this construction the tool is not rotated and consequently the rotating means are dispensed with.

The hammer 20 is forced upwardly by: the

pressure introduced below it from the com- ,pressor, and while risuie'. air pressure will he forced through pipe into the cylinder 6, and the spring 15 will be compressed. As the hammer 20 reaches its upper position,'a depression is created below the same bythe compressor; and'this will assist the descent of'the hammer 20 which is also pushedby the air pressure from cylinder 6 entering through pipe 22.

During the downward stroke of the piston 20, the suction from 21 exerted within the )iston said auxiliar iston bein ada ted.

to compress said auxiliary means during the operative stroke of the hammer piston, and said resilient means being adapted to force the auxiliary piston back to its original po sit-ion on the return stroke of the hammer.

piston and to force air from the auxiliary cylinder into the bore of the main cylinder for assisting in returning the hammer piston to its original position.

2. A pneumatic hammer as claimed in.

claim 1 in which the auxiliary piston is provided with an extension having helical grooves, a pinion arranged coaxially with the auxiliary piston and having internal said hammer piston, a toothed gear fixed to said tool and adapted to be driven by said pinion during the operativestroke of the hammer piston, and pawl for preventing reverse motion of the pimon on the return stroke of the hammer piston.

3. A pneumatic hammer comprising a ,main cylinder and an auxiliary cylinder, a .conduit placing one end portion or the in terior ot the main cylinder in communication with one end portion of the interior of the auxiliary cylinder, a pipe for conveying pulsating air to and from one end portion of the main cylinder, a tool having a stem extending into the interior of the main cylinder, a reciprocating piston hammer arranged in the main cylinder and adapted to strike said tool, an auxiliary piston arranged in the auxiliary cylinder and adapted to be moved in one direction by air pressure passing through said conduit from the main cylinder when the piston hammer moves in one direction. and resilient means arranged in the auxiliary cylinder and bearing upon the auxiliary piston for moving the same in an opposite direction and for V forcing air 7 through said conduit into the main cylinder when the hammer piston is moved in adirection opposite to its first mentioned move ment. i

a. A pneumatic hammer as claimed in claim 3 in which a hollow .cone is arranged withinthe main cylinder to limit the movehelical threads cooperating with said helical grooves, a tool arranged to be struck by ment of the piston hammer in one direction.

5. A pneumatic hammer as claimed in clalm 3 having drivingmeans arranged be- 5 tween the auxiliary piston and said tool for causing rotation of the tool as the auxiliary piston reciprocates.

6. A pneumatic hammer as claimed in claim 3 in Which a port is provided for placing one end of the auxiliary cylinder in communication with the atmosphere.

Signed at Milan (Italy), this 9th day of July 1920.

ERNESTO GURTI. 

